INFRARED REMOTE CONTROL DEVICE FOR A PERSONAL DIGITAL ASSISTANT

Abstract: According to the present invention there is provided an infrared code generating and transmitting device (12) adapted to be coupled to or incorporated in a microcomputer system (10), commonly referred to as a personal digital assistant (PDA). The IR code generating and transmitting device (12) comprises a CPU (40) separate or incorporated into the microcomputer system (10) of the PDA; a memory separate or incorporated into the microcomputer system (10); an LED output (IR1, IR2); LED driver circuitry (68) coupled between the CPU (40) and the LED output (IR1, IR2); an interface connector (78); an interface buffer circuit (44) coupled between the interface conector (78) and the CPU (40); and an interface data buffer circuit (54) coupled by data lines (80) between the interface connector (78) and the CPU (40).

Description: INFRARED REMOTE CONTROL DEVICE FOR A PERSONAL DIGITAL ASSISTANT BACKGROUND OF THE INVENTION 1. Field of the Invention. The present invention relates to an infrared (IR) code generating and transmitting device attached to or incorporated into a personal digital assistant (PDA) which is a microcomputer system in a hand-held case which typically will have an LCD screen, touch keys on a screen keyboard, and external ports for direct communication to a printer or desktop computer. One of the applications envisioned for a PDA is personal time management, calendar and schedule keeping. The IR code generating and transmitting device of the present invention coupled to or incorporated into a PDA expands the usefulness of the PDA by enabling same to be used for direct remote control of IR activated devices such as video (TV and VCR) and audio (CD and cassette player) equipment as well as IR activated home automation equipment. 2. Description of the related art. Heretofore, personal digital assistants (PDA's) have been proposed which can have a number of features incorporated into a microcomputer system mounted in the PDA with the casing of the FDA mounting an LCD screen including a digitizer for the capture of pen input. Eventually, PDA's will have software and hardware for converting handwriting to ASCII text. One or more PCMCIA slots can be provided for receiving a PCMCIA card containing customized data such as a local street map. Wireless communication can be provided for communicating via an IR transmitter, cellular phone or data packet radio whereby E-mail, faxes and voice messages can be downloaded. An antenna link can be provided in the PDA for communication with a global positioning system. This can help package delivery services track vehicles. A microphone can be built in for voice communication or document annotation. Additional external ports for direct communication to a printer or desktop computer can be provided. As will be described in greater detail hereinafter, the IR code generating/transmitting device of the present invention adds the capability to a PDA of activation and control of home video and audio equipment and home automation equipment. SUMMARY OF THE INVENTION According to the present invention there is provided an infrared code generating and transmitting device adapted to be coupled to or incorporated in a microcomputer system, commonly referred to as a personal digital assistant (PDA) . The IR code generating and transmitting device comprises a CPU separate or incorporated into the microcomputer system of the PDA; a memory separate or incorporated into the microcomputer system; an LED output; LED driver circuitry coupled between the CPU and the LED output; an interface connector; an interface buffer circuit coupled between the interface connector and the CPU; and an interface data buffer circuit coupled by data lines between the interface connector and the CPU. Also according to the present invention there is provided a method for generating and transmitting an IR command code from a microcomputer of the personal digital assistant (PDA) utilizing the infrared code generating and transmitting device described above, the method comprising the steps of: verifying that a BUSY signal on a busy line is not true; placing the desired data bits onto the data lines; allowing the data signal levels to stabilize; activating a -STROBE signal which, when active, is low; detecting the -STROBE signal; inputting the data byte into the CPU; asserting the BUSY signal to be true until inputting of the data byte has been completed; releasing the busy line by setting the BUSY signal to be not true; and pulsing or strobing an -ACK signal on an -ACK line to indicate that the IR code generating and transmitting device is ready to receive more data. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 of the drawings is a perspective view of one embodiment of a Personal Digital Assistant having attached thereto an infrared generating and transmitting device constructed according to the teachings of the present invention and physically and electrically connected to the Personal Digital Assistant. FIG. 2 of the drawings is a front end view of the Personal Digital Assistant and infrared generating and transmitting device shown in FIG. 1 and is taken along line 2-2 of FIG. 1. FIG. 3 is a block schematic circuit diagram of the electronic circuitry inside the infrared generating and transmitting device. FIG. 4 is a block flow diagram of the steps of a routine or protocol followed by the software/program in the infrared generating and transmitting device when carrying out a "RESET/INITIALIZATION SEQUENCE". FIG. 5 is a block flow diagram of the steps of a protocol or routine followed by the software/program in the infrared generating and transmitting device in carrying out a "RECEIVE DATA ROUTINE". FIG. 6 is a block flow diagram of the steps of a routine or protocol followed by the software/program in the infrared generating and transmitting device in carrying out a "SEND IR" command routine. FIG. 7 is a block flow diagram of the steps of a routine or protocol followed by the software/program in the infrared generating and transmitting device in carrying out a "CONTROL & SET-UP FUNCTIONS" routine. FIG. 8 is a timing diagram for typical interface timing between the Personal Digital Assistant and the infrared generating and transmitting device. DESCRIPTION OF THE PREFERRED EMBODIMENT(8) Referring now the drawings in greater detail, there is illustrated in FIG. 1 a so-called Personal Digital Assistant 10 which is an ultra-miniaturized hand held computer system. One such device is contemplated to be sold by Apple Computer Company under the trademark "NEWTON" and other such devices are sold by Casio Electronics. Similar devices are the Memorex "Commuter Computer", the Psion "Series 3" and the Zeos "Pocket PC". One of the applications envisioned for such hand held computer systems is personal time management, calendar keeping and schedule keeping. According to the teachings of the present invention, an infrared generating and transmitting device 12 is attached to (or can be incorporated into) the Personal Digital Assistant (PDA) 10 shown in FIG. 1. The function of such an infrared generating and transmitting device 12 is to enable the PDA to be capable of direct remote control of infrared (IR) operated devices such as video and audio entertainment systems, home automation systems and other IR operated systems. The technique for the capture, storage and subsequent generation of IR control signals is well known in the art and described in a number of prior patents, such as in the Darbee et al U.S. Patent No. 4,959,810. According to the teachings of the present invention, the IR generating and transmitting device 12 and IR generating and transmitting circuitry 14 (FIG. 3) attached to or incorporated into a PDA 10 is provided for use with or in a PDA 10 so that the ultra miniaturized hand held computer system can be used for IR control of various IR controlled systems, such as video and audio equipment including television sets, VCRs, compact disc players, etc. Referring now to FIG. 1 in greater detail, the PDA 10 has the IR generating and transmitting device 12 fixed to the underside thereof. Electronic IR generating and transmitting circuitry 14 (FIG. 3) is mounted in a casing 16 for the device 12 (or in the PDA 10) The casing 16 has a top panel 18 mounting a visual display or LCD screen 20 having touch sensitive keys 22 thereon. The panel 18 also mounts a speaker 24 and a microphone 26. One end 28 of the casing 16 has a parallel port 30 and a serial port 32 (FIG. 2) mounted thereon. As shown in FIG. 2, one end 34 of the IR generating device 12 has two light-emitting diodes (LED's) IRl and IR2 positioned thereon for emitting coded IR signals. Of course, the LED's IRl and IR2 can be incorporated into the PDA 10 as well as the IR generating and transmitting circuitry 14 to be described in greater detail hereinafter. As shown in FIG. 3, the IR generating and transmitting device 12 includes the electronic circuitry 14 including a microprocessor 40, including a RAM and a ROM with code therein for generating selected IR control signals on command. The IR LED's IRl and IR2 are coupled to the microprocessor 40 for transmitting the codes in IR format. A parallel interface 44 is provided which is coupled between the microprocessor 40 and a host microprocessor of the PDA (not shown) . Commands from the host PDA are supplied through the parallel interface 44 to the microprocessor 40. This circuitry enables the infrared generating and transmitting device 12 to be constructed as a separate add-on unit which can be externally attached electrically, for example, to a standard printer port (30 or 32) of the PDA 10. Of course, the interface 44 can be different, such as, for example, a serial interface for connection to a serial port (32) of a PDA 10; or, as stated above, the interface could be eliminated and the IR LED's IRl and IR2 can be incorporated as a built in feature of the PDA 10 and the microprocessor of the PDA would also be utilized as the IR microprocessor, either by means of a circuit board plugged into an internal expansion slot, an external expansion slot such as a PCMIA slot, or as an integral part of the main computer board itself. Alternatively, the IR microprocessor 40 can be eliminated entirely and the microprocessor of the PDA can be utilized instead with an IR LED driver attached as a peripheral to the main microprocessor of the PDA which will then directly execute appropriate software to generate the desired IR signal codes. The electronic circuitry 14 of the IR generating and transmitting device 12 is shown in detail in FIG. 3. Here a voltage divider circuit 46 is provided and includes first and second resistors Rl and R2 which together with a capacitor Cl define the voltage divider 46 and ensure a clean reset signal for the microprocessor 40 whenever power is applied. The voltage divider circuit 46 is coupled to +Vcc through a buffer interface circuit 54 and a and a pull up resistor R3 which permit initiation of the microprocessor 40 reset through the external buffer interface circuit 54 by a signal "INITIALIZE". The steps of the protocol carried out by the software on receipt of the "RESET" command will be described in greater detail in connection with the description of the RESET INITIALIZATION SEQUENCE illustrated in FIG. 4. A voltage backup and conditioning circuit 58 is provided which conditions the power supplied from the voltage divider circuit 46 to the microprocessor 40. A diode Dl and a capacitor C2 insure a stable supply of voltage from a power supply Jl to the microprocessor 40 even during high current demand cycles which may occur during transmission of IR code signals. A second diode D2, a series connected lithium battery 60, and a parallel connected capacitor C3 provide backup power for maintaining the data in the RAM of the microprocessor 40 when power is withdrawn. The electronic circuitry 14 further includes an oscillator circuit 64 including a ceramic resonator Yl, a first capacitor C4, a second capacitor C5 and a resistor R5. The oscillator circuit 64 is, in effect, a clock circuit for the microprocessor 40. An IR driver circuit 68 is coupled to the microprocessor 40, as shown, and includes a first transistor 70 and a second transistor 72 connected as a Darlington Pair for driving the dual IR LEDs IRl and IR2 under the control of a signal received through a capacitor C6 from output pin PB7 of the microprocessor 40 which changes the voltage drop across a resistor R5 connected between +Vcc and the base of transistor 72. The software action comprises steps carried by a program stored in the RAM of the microprocessor 40 for initiating and controlling transmission of IR codes will be described in greater detail in connection with the description of the RECEIVE DATA ROUTINE illustrated in FIG. 5 which is the protocol carried out in a SEND IR command. A 36 pin industry standard interface connector 78 is provided and is often referred to as a "Centronics" interface after the name of the first manufacturer to propose its use. Connected between the microprocessor 40 and the interface connector 78 is the buffer interface circuit 44 which is a 74LS374 buffer which buffers 8 bits of data received over eight interface lines 80. The data bits present on the input pins DO through D7 are latched into the buffer interface circuit 44 by an interface signal, -STROBE (after being conditioned by an inverter gate 82) . A timing diagram for the typical interface timing is illustrated in FIG. 8 and is described in greater detail in connection with the description of the timing diagram shown in FIG. 8. An interrupt circuit comprising two inverters 84 and 86 are coupled from the strobe input line 88 to an interrupt input IRQ- of the microprocessor 40. The same interface signal, namely the -STROBE signal after conditioning and a delay through the two inverter gates 84 and 86, which are 74LS04 gates, initiates operation of the microprocessor 40 upon receipt of the data from the buffer interface circuit 44. In this respect, the -STROBE signal drives the IRQ pin of the microprocessor 40 low thereby generating an interrupt to the operating software of the microprocessor 40. The steps of the program/software entitled RECEIVE DATA that are carried out by the microprocessor 40 upon receipt of the interrupt signal is illustrated in FIG. 5. The interface buffer circuit 54 is a 74LS244 buffer and is used as a buffer for two outputs from the microprocessor 40, the two output signals being a BUSY signal and an -ACK signal from the microprocessor 40. The interface buffer circuit 54 also buffers an input signal, INITIALIZE. The relationship of the BUSY and -ACK signals is illustrated in FIG. 8 and the steps of software or program control thereof, entitled RECEIVE DATE ROUTINE is illustrated in FIG. 5. The hardware interface between the PDA 10 and the IR generating and transmitting device 12 comprises 8 data lines and 6 control lines 90. The control line INITIALIZE enables the PDA 10 to reset the IR microprocessor 40 to a known state as indicated in FIG. 3. Control lines SLCT and -ERROR are not used in this application, and are hardwired (to Vcc) to their normal state to ensure compatibility with standard printer interface specifications. Control lines -STROBE, BUSY, and -ACK manage the transfer f data across the interface buffer circuit 44 in the following manner with reference to FIG. 7. The PDA 10, after verifying that the BUSY signal is not true, places the desired data bits for initiating the transmission of the desired IR code signal onto the 8 data lines 80. After a short period of time to allow these signal levels to stabilize, the PDA 10 then activates the -STROBE signal (note that -STROBE is active low) . Upon detection of the -STROBE signal, the microprocessor 40 reads in the 8 bit data byte and asserts the BUSY signal. The BUSY signal remains true until the data byte has been processed (i.e. the function requested has been completed), at which time the microprocessor 40 releases the BUSY signal and pulses -ACK to indicate that it is ready to receive another byte. A flow chart of the steps followed by the software in carrying out a RESET/INITIALIZATION SEQUENCE is shown in FIG. 4. After a reset signal has been activated, a ram checksum determination is made to make certain that the default value for the device type(s) are correct. Then the interface I/O line signals are initialized, e.g., a BUSY signal on a PCO pin of the microprocessor 40 is set low and the -ACK signal on pin PCI is set high. Next all the internal software flags are cleared and the interrupt is enabled. In FIG. 5 is illustrated a flow chart of the steps of the software that are carried out in a RECEIVED DATA ROUTINE. Here the interrupt (-STROBE signal) activates the microprocessor 40 to set the BUSY signal on the PCO pin to be true. Then the data byte from the input lines to pins PA0-PA7 is received. Next a determination of the start of a control sequence is made so that the control and set up functions can be performed as illustrated in FIG. 7. If no control status is on, then the IR command is sent as illustrated in FIG. 6. Next the BUSY signal at the PCO pin is set FALSE followed by a strobe -ACK signal being placed on the ACK line at pin PCI. When the IR generating and transmitting circuitry 14 is attached to the PDA printer port, the PDA 10 can issue two types of commands as illustrated in the flow chart in FIG. 4. Normal operational commands are shown in FIG. 5 and are 1-byte values which cause IR code signals to be transmitted to a target device to be controlled such as a television or VCR. The code signal transmitted in response to a specific byte depends on the particular device type/make/model selected. However, in general, these code signals can be thought of as each byte being the equivalent of a single keystroke on a normal remote control device. The second class of command signals from the PDA 10 comprise function signals which control the operation and configuration of the microprocessor 40 and generally consist of more than one byte of information. The start of one of these control function transmit sequences is indicated by the receipt of a special (reserved) byte value. This causes the software/program in the microprocessor 40 to set the microprocessor 40 into a "Control Mode" status such that subsequent bytes are interpreted as control functions and not IR commands as illustrated in the flow chart set forth in FIG. 4. Two types of control functions are currently defined in FIG. 6. The first is a mode change. This specifies the particular class of device (TV, VCR, cable box, CD player, radio receiver, tape deck, etc.) to be controlled by subsequent IR commands. The microprocessor 40 permits multiple modes of classes each with a particular device/make/model assigned to it. This allows rapid switching back and forth between an array of several devices to be controlled. The second type of control function specifies the particular device make and/or model within the mode (e.g. TV) currently selected. This consists of a 3-digit number which when referenced against a built in code library in the ROM or RAM of the microprocessor 40 and the IR generating and transmitting circuitry 14, uniquely specifies the IR code format for the particular device and the transmission parameters for transmitting a code to the particular device to be controlled. FIG. 6 is a flow chart of the steps carried out by the software in the microcomputer when it receives a SEND IR command. First, the identity of the current device is loaded. Then, using the device type and the data byte received the microcomputer 40 indexes into an "IR command" library. Next a determination is made if the command is valid. If no, the program exits. If yes, the transmission parameters are obtained from the library, e.g., carrier frequency encoding data, format, etc. Then the program points to a first on/off time. Next the time is set for a carrier "ON" time. Then a carrier generator code loop is executed for the "ON" time. Next the timer is set for carrier "OFF" time. Then no operation is executed and a determination if the "ON" time is completed. Then a determination is made if the code pattern has been completed. If not, the program returns to the "point to first on/off time" step. When the pattern is completed, a determination is made if it should be repeated. FIG. 7 illustrates the steps followed by the software/program in the microcomputer in effecting the CONTROL & SET-UP FUNCTIONS. In implementing the routine for the CONTROL & SET-UP FUNCTIONS, once a command to control and set-up is determined (see FIG. 5) , a determination of a digit number and first or second digit is made. If the digit is not between 0 and 9, a determination is made if a mode change command is being sent via the keyboard 22. If yes, a new mode is set. After determination of the digits has been completed and it is determined that the digit was not a first or second digit, the third digit is obtained and combined with the other two digits to form a device number. Then a determination is made if it is a valid 3-digit device number. Then the IR generating and transmitting device circuitry 14 is set for the new device type for the current mode followed by clearing of all internal flags and setting of the control status to off. A typical interface timing diagram is illustrated in FIG. 8 where it can be seen that the -STROBE signal is initially high and then goes low causing the BUSY signal to go high. Then a data valid check is made and if valid, the function or command is performed after which the BUSY signal goes low and then a strobe -ACK low signal is transmitted from the pin PCI through the interface buffer circuit 54 and the interface connector 78 to the PDA 10. From the foregoing description, it will be apparent that the IR generating and transmitting device 12 of the present invention as an adjunct incorporated into a PDA 10 enhances the value and use of a PDA. More specifically, it enables the PDA 10 to be used as a remote control for controlling IR controlled devices such as for example televisions, VCRs, garage door openers, IR controlled lighting systems, and other IR controlled devices on machines. Also it will be apparent from the foregoing description that modifications can be made to the IR generating and transmitting device 12 of the present invention without departing from the teachings of the invention. Accordingly, the scope of the invention is only to be limited as necessitated by the accompanying claims.

Claims: CLAIMS We Claim: 1. An infrared code generating and transmitting device adapted to be coupled to or incorporated into a microcomputer system commonly referred to as a personal digital assistant, said IR code generating and transmitting device capable of generating a plurality of IR control signals suitable for control of video and home entertainment systems and home automation systems based upon stored program information, and comprising: a CPU separate or incorporated into a microcomputer system; memory means separate or incorporated into said microcomputer system; LED output means; and LED driver circuitry coupled between said CPU and said LED output means. 2. The device of claim 1 including: an interface connector. 3. The device of claim 2 including: interface buffer circuit means coupled between said interface connector and said CPU; and an interface data buffer circuit coupled by data lines between said interface connector and said CPU. 4. The device of claim 3 including control lines between said interface connector and said first and second buffer circuit means. 5. The device of claim 4 wherein said control lines include a BUSY line and an -ACK line between said interface connector and said first buffer circuit means and a -STROBE line between said interface connector and said second interface buffer circuit means. 6. The device of claim 5 wherein said -STROBE line is coupled through an inverter to said second data interface buffer circuit means. 7. The device of claim 5 wherein said -STROBE line is coupled between said interface connector and an interrupt port of said CPU through first and second inverter gates. 8. A method for generating and transmitting an IR command code from a microcomputer system known as a personal digital assistant (PDA) utilizing an infrared code generating and transmitting device comprising: a CPU separate or incorporated into a microcomputer system; memory means separate or incorporated into the microcomputer system; LED output means; LED driver circuitry coupled between the CPU and the LED output means; an interface connector; interface buffer circuit means coupled between the interface connector and the CPU; and an interface data buffer circuit coupled by data lines between the interface connector and the CPU, the method comprising the steps of: verifying that the BUSY signal on the busy line is not true; placing the desired data bits onto the data lines; allowing the data signal levels to stabilize; activating a -STROBE signal which, when active, is low; detecting the -STROBE signal; inputting the data byte into the CPU; asserting the BUSY signal to be true until inputting of the data byte has been completed; releasing the busy line by setting the BUSY signal to be not true; and pulsing or strobing an -ACK signal on an -ACK line to indicate that the IR code generating and transmitting device is ready to receive more data.

Inventors: DARBEE PAUL V, DARBEE, PAUL, V.
Applicants: DARBEE PAUL V, UNIVERSAL ELECTRONICS INC, DARBEE, PAUL, V., UNIVERSAL ELECTRONICS, INC.
Application year: 1994
Main classification: H04B10
IPC codes: G06F1, G06F15, H03J1, H03J9, H04B1, H04B10, H04Q9